It is proposed to continue studies of the structure and organization of the cerebral cortex using the combined Golgi electron microscope procedure whereby individual neurons identified in Golgi preparations can be gold-toned to allow the neurons to be examined in the electron microscope. The neurons to be examined include the myelinated multipolar, sparsely-spined and smooth stellate cells; spiny stellate cells and bipolar cells of the rat visual cortex. The synaptic relationships of these neurons will be studied to assess their role in the connectivity of the cortex. Work will also be initiated on the monkey visual cortex to determine the types of neurons present and to begin study of some of these neurons using the combined Golgi/electron microscope technique to determine if they are similar to those present in the rat visual cortex. Attention will also be paid to the rat retrosplenial cortex to see if this simple type of cortex, with clearly defined thalamic and callosal afferent inputs, can aid in better interpreting the organization of the neocortex.